This invention relates generally to automatic measuring and testing apparatus and more particularly to an apparatus for testing fruit and fruit juice and for computing a variety of characteristic parameters which are accepted in the citrus fruit industry as indicating the nature and quality of the fruit or fruit juice.
In the fruit growing industry and particularly in the citrus fruit growing industry, fruit is harvested from the groves and transported to terminals or processing plants for sale. The selling price of the fruit crop is largely determined by the nature and quality of the fruit.
Conventionally, the fruit quality is determined by a variety of laboratory like tests which are manually performed away from controlled laboratory conditions. These tests include the determination of the soluble solids content, commonly measured in degrees Brix, and the acid content of the juice, commonly measured as a per cent acid. The results of these tests are used in computations to determine characteristic parameters of the sample fruit, which characteristic parameters include the ratio of soluble solids content to acid content, the weight of juice in a standard box of fruit, and the weight of soluble solids in a standard box of fruit.
These tests are conventionally manually performed and the results thereof depend to a large degree upon the eyesight and judgement of the inspector performing the tests. In addition, there is great opportunity for introducing error in this type of arrangement due to the manual transferring the test data to the computational stage, the opportunity for incorrectly performing the computations, or the possibility of attributing the results of a particular computation to the wrong fruit sample. As a result, this testing process has heretofore been a long and tedious operation whose results were not highly reliable.
There is, therefore, a need for a means which is capable of performing these tests which requires a minimum of operator interaction, performs the tests and does the necessary calculations in a minimum amount of time, and reduces errors.
The present invention solves this need by providing an automatic fruit analyzer which automatically performs the required tests and calculates the desired parameters with a minimum of operator interaction, in a minimum amount of time, and to a high degree of accuracy.
Apparatus for determining the specific gravity of a liquid is well known in the art and includes the devices disclosed in Gipe et al, U.S. Pat. No. 1,205,986, Burningham et al, U.S. Pat. No. Re. 17,728, Wallace, U.S. Pat. No. 3,071,971, Weichselbaum et al, U.S. Pat. No. 3,332,289 and Fann, U.S. Pat. No. 3,821,901. Similarly, apparatus for automatically titrating liquids is known and includes the devices shiwn in Prohaska, U.S. Pat. No. 3,730,685, and Rellstab et al, U.S. Pat. No. 3,870,466.
Although the use of a float type arrangement for use in the determination of the specific gravity of a liquid is known in the art, none of the cited references discloses a float type arrangement in conjunction with a load cell transducer yielding an analog output proportional to the forces exerted on the float type arrangement. Additionally, none of the cited references provides a means whereby errors introduced into the measurement process by a change in weight of the float type arrangement, for example caused by a build-up of deposits thereon, may be eliminated. Even further, none of the references discloses a means for eliminating the errors introduced into the specific gravity measurement by the temperature of the liquid being measured.
None of the above cited references relating to apparatus for automatic titration discloses an automatic means for titrating by weight. Titration by weight allows a much simpler and more economical apparatus to be used for the titration process since very accurate volumetric measurements are not required to perform the titration process.
In general, previous attempts to mechanize acid content or soluble solids content testing equipment, particularly those using refractometers, have attempted to control and standardize all of the conditions of the test sample. For example, they attempted to maintain the juice at an exact temperature and precisely control the flow rate of juice during the test. Consequently, variations in the conditions of the test sample caused variations in the accuracy of the test data. The difficulties in controlling the conditions of the test sample made automation of the test procedure effectively impossible due to the large number of highly variable factors involved. The present invention eliminates this problem by correcting for changes in the test sample.